1. Field of the Invention
The present invention relates to a MIDI (Musical Instrument Digital Interface) control apparatus to control a MIDI instrument and a MIDI system incorporating such a control apparatus.
2. Description of the Related Art
A MIDI standard is necessary in order that musical instruments such as a synthesizer or an electronic piano can be connected to each other and exchange of information therebetween is possible.
An electronic musical instrument provided with hardware according to such MIDI standard and having the function of transmitting/receiving MIDI control signals as instrument play control signals with form defined to carry musical information is called a MIDI instrument.
In discs such as CD (compact disc) , CD-V (video), LD (laser disc) including CD format digital audio and tapes used by a tapedeck such as a DAT (Digital Audio Tape), a subcode carrying play control information or the like is recorded. The subcode is constituted by P, Q, R, S, T, U, V, W channels, and among these, the P and Q channels are used as control signals for a disc player.
On the other hand, the R - W channels become empty channels called user's bits, and various applications are studied such that information of graphic, voice, picture or the like is recorded, and a standard regarding a graphic format has been always proposed.
MIDI format signal can be also recorded in the user's bits, and a standard regarding this has been already proposed. In this case, not only is the audio video signal reproduced by the disc player is supplied to AV (Audio Visual) system and the program recorded in the disc is viewed and heard but also the play program information can be supplied to one or more MIDI instruments placed side by side with the AV system, thereby forming an AV system with presence including electronic musical instruments, the preparation of software for the education and other various applications are studied.
The MIDI instrument plays in accordance with the instrument play program formed by the MIDI signal and MIDI format signals supplied in sequence from the disc player are converted into serial signal. However, when the disc player supplies the instrument play program, if command of the operation accompanied by a track jump or a pause operation is received, the MIDI instrument cannot continuously read out the instrument play program in the writing order of the instrument play program and therefore the continuity of the instrument play program is interrupted. As a result, a malfunction may be produced such that the sound generated from the sound source of the MIDI instrument is not stopped.
The reason will be specifically described as follows.
First, the MIDI signal supplied to the MIDI instrument is serial data of the transfer rate 31.25 [Kbaud], and one byte of data is constituted by 10 total bits including 8 bits of data a start bit and a stop bit.
In order to designate the sort of transmitted data or the MIDI channel, at least one status byte and one or two data bytes led by the status are combined, thereby forming a message as the musical information. Consequently, one message is constituted by 1-3 bytes, and a transfer time of 320-960 [.mu. sec] is required for the transfer. The instrument play program is formed by a series of these messages.
FIG. 1 shows the structure of a note-on-message as an example of such a message.
The note-on-message in the status byte is the command corresponding to the operation of pressing a key or keyboard, and is used in a pair along with a note-off-message corresponding to the operation of releasing the key on the keyboard. For example, as shown in FIG. 2(A), sounds 1, 2 are produced by the note-on-message, and stopped by the note-off-message corresponding to the note-on-message. The note number of the data byte 1 assigns any of 128 stages assigned to the keyboard about "the center C" of an 88-key piano. The velocity of the data byte 2 is utilized to provide differences in the intensity of the sound. The MIDI instrument receiving the note-on-message generates a sound corresponding to the scale and the assigned intensity. On receiving the note-off-message, the MIDI instrument to stops the generation of the sound.
As shown in FIG. 2(B), after the note-on-message is transmitted to the sound source and before the note-off-message is transmitted, if a track jump, such as a manual search, a track search or the like or a state occurs on an error operation such, as pause, stop or the like the continuity of the instrument play program by the MIDI signal is partially lost or the progress of the program is stopped with the lapse of time. As a result, a malfunction is produced in that the sound 1 is not stopped because there is no note-off-message. In the pause state, usually as shown in FIG. 3, a pickup performs the track jump and repeatedly traces one track T (broken line indicates other track) of the disc 1. By transfer from the play state to the pause state, the player repeatedly generates a MIDI signal including the the reapeat track and play becomes discontinuous. Particularly, when plural sorts of the sound sources are performed simultaneously so that they overlap, such a malfunction cannot be easily dealt with.
Such malfunction is not limited to a the case in which there is no note-off-message, but may also occur when the control operation, such as modulation channel pressure, pitch bent hold, or breath control must be stopped.